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IAA UK max bid calculator
Put in what the car will sell for and what it will cost you, and this works back to the most you can bid. It uses IAA UK's own fee bands: the buyer fee, the admin fee, the £50 retrieval fee and 20% VAT on all three. Free, no sign-in.
Fee bands from IAA UK's fee table, last updated by IAA on 1 April 2026 and checked on 3 October 2026. Your numbers stay in your browser.
Check the car before the numbers
The IAA and Marketplace pre-checks take you through a listing step by step and stop you at the deal breakers: Cat S, no keys, outstanding finance, over 125,000 miles. They're in the member tools. Sign in with your email, no password, and your phone or laptop is remembered after the first time.
How the max bid is worked out
Most people start from the hammer price and add things on. This calculator works the other way round, from the sale price down, so you know your walk-away number before the auction starts.
- Start with the clean retail ceiling. That's what a fixed, clean example of the same car really sells for: same model, year and engine, and roughly the same mileage. Use sold prices or the cheapest sensible adverts, not the dearest asking price. If the car is a Cat N, compare it with other Cat N cars.
- Take off the profit you want. The beginner rule in the member tools is at least £500 or 20% of the sale price, whichever is more.
- Take off everything it costs to get the car on sale: parts, any labour you pay for, a contingency on top of those repairs (10% to start with, because something always turns up), transport, the HPI check, and the MOT, valet, advert and fuel.
- What's left pays for the hammer price and IAA's fees. The fees rise in steps with the hammer price, so the calculator tries every bid in £10 steps and keeps the highest one where the bid, the buyer fee, the admin fee, the £50 retrieval fee and 20% VAT on those three still fit. That's your max bid.
The Cost of a bid tab runs it the other way. Type a hammer price and it adds every fee and cost on top, shows what you'd pay IAA on the day and tells you whether the profit left is inside your target.
Worked example
A car that sells for £3,500 clean. It needs £450 of parts, you do the work yourself, transport is £120, the HPI check £20 and the MOT, valet, advert and fuel £70. You want £800 profit, you're on standard fees and the lot has no VAT on the hammer. These are the calculator's example numbers.
| Hammer price | £1,520.00 |
|---|---|
| IAA buyer fee (standard, £1,500.00 to £1,599.99 band) | £265.00 |
| IAA admin fee (£1,500.00 to £1,999.99 band) | £79.00 |
| Retrieval fee | £50.00 |
| VAT on the three fees (20%) | £78.80 |
| Paid to IAA | £1,992.80 |
| Parts | £450.00 |
| Contingency (10% of parts and labour) | £45.00 |
| Transport | £120.00 |
| HPI check | £20.00 |
| MOT, valet, advert, fuel | £70.00 |
| All-in cost | £2,697.80 |
| Sale price | £3,500.00 |
| Profit | £802.20 |
One more £10 step, to £1,530, would leave £792.20, under the £800 target. So £1,520 is the max bid.
Watch the band edges. Going from £990 to £1,000 takes the buyer fee from £200 to £215 and the admin fee from £49 to £69, so that extra £10 of bid adds £52 to your bill.
This is a worked example, not a prediction. Every car's numbers are different, and some flips lose money.
The IAA UK fees in this calculator
IAA UK quotes its fees before VAT. Every car you win has a buyer fee and an admin fee, both set by the hammer price, plus a £50 retrieval fee, and 20% VAT goes on all three. VAT on the hammer price itself only applies to lots marked VAT applicable.
Standard fees apply if you've bought 12 or fewer vehicles in a rolling 12 months. High volume fees apply above that, so most beginners pay standard.
| Hammer price | Standard | High volume |
|---|---|---|
| £0.01 to £49.99 | £10.00 | £0.00 |
| £50.00 to £99.99 | £55.00 | £10.00 |
| £100.00 to £199.99 | £75.00 | £35.00 |
| £200.00 to £299.99 | £95.00 | £55.00 |
| £300.00 to £349.99 | £105.00 | £65.00 |
| £350.00 to £399.99 | £115.00 | £75.00 |
| £400.00 to £449.99 | £125.00 | £85.00 |
| £450.00 to £499.99 | £130.00 | £90.00 |
| £500.00 to £549.99 | £135.00 | £95.00 |
| £550.00 to £599.99 | £140.00 | £105.00 |
| £600.00 to £699.99 | £155.00 | £115.00 |
| £700.00 to £799.99 | £170.00 | £130.00 |
| £800.00 to £899.99 | £185.00 | £145.00 |
| £900.00 to £999.99 | £200.00 | £160.00 |
| £1,000.00 to £1,199.99 | £215.00 | £175.00 |
| £1,200.00 to £1,299.99 | £235.00 | £195.00 |
| £1,300.00 to £1,399.99 | £245.00 | £205.00 |
| £1,400.00 to £1,499.99 | £255.00 | £215.00 |
| £1,500.00 to £1,599.99 | £265.00 | £225.00 |
| £1,600.00 to £1,699.99 | £275.00 | £235.00 |
| £1,700.00 to £1,799.99 | £290.00 | £250.00 |
| £1,800.00 to £1,999.99 | £300.00 | £260.00 |
| £2,000.00 to £2,399.99 | £330.00 | £290.00 |
| £2,400.00 to £2,499.99 | £355.00 | £315.00 |
| £2,500.00 to £2,999.99 | £380.00 | £340.00 |
| £3,000.00 to £3,499.99 | £415.00 | £375.00 |
| £3,500.00 to £3,999.99 | £455.00 | £415.00 |
| £4,000.00 to £4,499.99 | £500.00 | £460.00 |
| £4,500.00 to £4,999.99 | £525.00 | £485.00 |
| £5,000.00 to £5,999.99 | £545.00 | £505.00 |
| £6,000.00 to £7,499.99 | £555.00 | £515.00 |
| £7,500.00 to £9,999.99 | £580.00 | £540.00 |
| £10,000.00 and over | 6.4% | 5.4% |
| Hammer price | Admin fee |
|---|---|
| £0.00 to £99.99 | £0.00 |
| £100.00 to £499.99 | £35.00 |
| £500.00 to £999.99 | £49.00 |
| £1,000.00 to £1,499.99 | £69.00 |
| £1,500.00 to £1,999.99 | £79.00 |
| £2,000.00 to £3,999.99 | £89.00 |
| £4,000.00 to £5,999.99 | £99.00 |
| £6,000.00 to £7,499.99 | £105.00 |
| £7,500.00 and over | £109.00 |
| Retrieval fee, every vehicle | £50.00 |
| VAT on the buyer, admin and retrieval fees | 20% |
| Late payment, after 72 hours | £40.00 |
Source: IAA UK help centre, What are IAA Buyer Fees?, last updated by IAA on 1 April 2026 and checked on 3 October 2026. The late payment charge isn't in the calculator. Fees change, so check IAA's page before a big bid.
Questions people ask
What fees do IAA UK charge?
Three fees on every car you win, all quoted before VAT: a buyer fee and an admin fee that both rise with the hammer price, and a £50 retrieval fee. VAT at 20% goes on all three. On a £1,000 hammer price a standard buyer pays a £215 buyer fee, a £69 admin fee and the £50 retrieval fee: £334.00, or £400.80 with VAT, so £1,400.80 in all. From £10,000 the buyer fee is a percentage of the hammer price: 6.4% standard, 5.4% high volume. IAA also charges £40 if you don't pay within 72 hours of the sale.
How much should I bid on a Cat N car?
Work back from what a clean, fixed example really sells for as a Cat N. Take off the profit you want, the repairs with a contingency on top, transport, the HPI check and your selling costs, then IAA's fees and the VAT on them. What's left is your max bid. Set it before the auction starts and don't go over it. The beginner rule in the member tools is a profit of at least £500 or 20% of the sale price, whichever is more.
Do you pay VAT at IAA UK auctions?
You pay 20% VAT on IAA's fees on every car. You only pay VAT on the hammer price when the lot is marked as VAT applicable, which is more common on vans and ex-fleet cars than on private cars. Check the listing, and set VAT on the hammer price to Yes in the calculator for those lots.
Is a Cat N car worth buying to flip?
It can be, if the numbers work. Cat N means the damage wasn't structural, which is why it's where most beginners start. The write-off marker stays on the car's record, so it sells for less than the same car without one: price your sale against other Cat N cars and tell buyers about the category in writing. Cat S means structural damage, and the member tools treat it as a walk-away for beginners.
Does this calculator work for Copart UK?
Not for the fees. Copart UK has its own fee table and this calculator only has IAA UK's, so the max bid won't be right for a Copart lot. The method is the same: work back from the sale price. Get Copart's current fees from Copart before you bid.
Bring a car to the Thursday live
Every Thursday at 7pm UK time, members bring listings from IAA, Copart and Facebook Marketplace and Kieran goes through them live: the MOT history, the likely repairs, what the car will sell for and the most he'd pay. It's part of Car Flip Academy UK, which is free to join.